What is faith

"Doubt is pain
Too lonely to know
That faith is his twin brother."
Khalil Gibran

So what is faith?
It could simply be put as the lack of doubt.
Then what is doubt?
Doubt is insecurity, fear, hesitation
Doubt is everything that knocks you of your balance.
Doubt is everything that is unnecessary.
So let go of it
Simply trust
But first you need to trust in yourself.